1. Field of the Invention
The present invention relates to a tension controller for applying tension to a cable used to move an opened-and-closed body attached to a vehicle body and also relates to an opening and closing device for vehicle having the same.
2. Description of the Related Art
An opening and closing device for vehicle has been disclosed in Japanese Patent Provisional Publication No.9-256732. In the opening and closing device for vehicle, a cable has a central portion to be wound around a rotary drum and both end portions to be connected to a sliding door. The cable is passed through flexible conduits in the vicinity of both sides of the rotary drum and wired along a rail for guiding the sliding door. The cable is wound around the rotary drum and fed from the rotary drum at the same time to move the sliding door along the rail in the desired direction. Further, the cable is passed through two tension controllers. One tension controller is disposed between the rotary drum and one conduit, and the other tension controller is disposed between the rotary drum and the other conduit.
The tension controller applies tension to the cable fed from the rotary drum to take up the slack. The tension controller has a sliding case, a tension pulley and a compression spring. The sliding case rotatably supports the tension pulley at one end portion thereof and receives the compression spring therein. The tension pulley abuts on the cable fed from the rotary drum. The compression spring always biases the tension pulley toward the cable and applies tension to the cable to take up the slack.
Besides, another opening and closing device for vehicle has been disclosed in Japanese Patent Provisional Publication No. 2001-115736. The opening and closing device for vehicle has a cable drive unit. The cable drive unit includes a base bracket, a motor, a rotary drum and a transmission. The base bracket is fixed to a vehicle body. The motor generates driving force to rotate the rotary drum. The rotary drum has an external peripheral surface on which the central portion of a cable connected to a sliding door is wound. The transmission reduces the number of revolutions of the motor and transmits it to the rotary drum. The motor and the transmission are disposed on one side of the base bracket, and the rotary drum is disposed on the other side of the base bracket. In the above structure, the opening and closing device for vehicle allows the rotary drum to rotate in the predetermined direction by transmitting the numbers of revolutions of motor to the rotary drum via the transmission. Thereby, the cable is wound around the rotary drum and fed from the rotary drum at the same time to move the sliding door along the rail in the desired direction.
The former opening and closing device has the following problem. In the attaching operation of the cable, both end portions of the cable are connected to the sliding door after the cable is attached to the rotary drum and the tension controllers. Therefore, it is necessary to connect both end portions of the cable to the sliding door while the cable is stretched out against the biasing force of the compression spring, resulting in difficulty in the attaching operation of the cable.
The latter opening and closing device has the following problems. The motor and the transmission are disposed on one side of the base bracket, and the rotary drum is disposed on the other side of the base bracket. Therefore, the cable drive unit has a larger thickness, resulting in a smaller space within the interior of a vehicle. Because of the restriction on its structure, it is difficult to attach the same type of cable drive units on both the right and left sliding doors. Further, since there is not a tension controller in this device, the slack will occur in the cable fed from the rotary drum.